U.S. patent number 5,249,449 [Application Number 07/872,484] was granted by the patent office on 1993-10-05 for can necking apparatus with spindle containing pressurizing gas reservoir.
This patent grant is currently assigned to Reynolds Metals Company. Invention is credited to Harry W. Lee, Charles T. Payne, Jr., Field I. Robertson, Robert K. Thai.
United States Patent |
5,249,449 |
Lee , et al. |
October 5, 1993 |
Can necking apparatus with spindle containing pressurizing gas
reservoir
Abstract
A method and machine for forming can necks in metal container
bodies is disclosed. The machine comprises a pilot assembly
coaxially situated and longitudinally movable with respect to and
within a necking die member having an annular static die forming
surface longitudinally advanced into contact with the can side wall
defining the open end. Prior to necking, the pilot assembly is
inserted into the open end and then stopped. Continued forward
movement of the necking die member opens a valve between the pilot
assembly and die member to flow pressurized fluid from a reservoir
in the pilot to pressurize the can. This prevents crushing of the
can under necking loads. The reservoir is located entirely within
the pilot shaft and has a dimensional volume greater than the can
body interior volume. This results in rapid delivery of pressurized
fluid into the can before the greatest necking loads are applied to
the side wall.
Inventors: |
Lee; Harry W. (Chesterfield
County, VA), Payne, Jr.; Charles T. (Chesterfield County,
VA), Robertson; Field I. (Chesterfield County, VA), Thai;
Robert K. (Richmond, VA) |
Assignee: |
Reynolds Metals Company
(Richmond, VA)
|
Family
ID: |
25359655 |
Appl.
No.: |
07/872,484 |
Filed: |
April 23, 1992 |
Current U.S.
Class: |
72/352; 413/69;
72/379.4 |
Current CPC
Class: |
B21D
51/2638 (20130101); B21D 51/2615 (20130101) |
Current International
Class: |
B21D
51/26 (20060101); B21D 041/04 () |
Field of
Search: |
;72/57,94,352,356,379.4
;413/69 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Larson; Lowell A.
Attorney, Agent or Firm: Lyne, Jr.; Robert C.
Claims
We claim:
1. A method of necking an open end of a metal container, comprising
the steps of:
(a) inserting a pilot die into the container through said open end
to be necked;
(b) contacting an exterior surface of said open end with a necking
die to thereby produce a necked-in open end; and
(c) pressurizing the interior of the metal container by admitting
fluid into it during step (b) from a reservoir located in the pilot
die and containing pressurized fluid, wherein the dimensional
volume of said reservoir is at least about equal or greater than
the volume of the metal container.
2. The method of claim 1, wherein step (b) occurs as a result of
relative movement between the pilot die and necking die.
3. The method of claim 2, comprising the further step of
continuously pressurizing the reservoir during step (c) from a
supply of pressurized fluid flowing thereto.
4. The method of claim 1, wherein said reservoir is pressurized to
about 60 psi which enables pressurization of the container interior
to about 20-25 psi within about 15 milliseconds.
5. A method of necking an open end of a metal container, comprising
the steps of:
(a) inserting a pilot die into the container through said open end
to be necked;
(b) contacting an exterior surface of said open end with a necking
die to thereby produce a necked-in open end; and
(c) pressurizing the interior of the metal container by admitting
fluid into it during step (b) from a reservoir located in the pilot
die and containing pressurized fluid, of the reservoir, said
throughbores being normally closed in a relatively retracted
position of the necking die by a valve element carried by said
necking die, said throughbores being open as the valve element is
advanced out of closing contact as a result of forward movement of
the necking die into necking contact with the open end.
6. The method of claim 5, wherein said reservoir communicates with
the container interior during the entire time the container is
being necked.
7. The method of claim 6, comprising the further steps of moving
the necking die rearwardly to begin withdrawal from the container
while maintaining the pilot die substantially stationary within the
container so that the valve element on the necking die contacts the
valve disc to seal the reservoir from the container interior;
whereby further retraction of the necking die causes retraction of
the pilot die from the container interior.
8. The method of claim 7, comprising the further step of stripping
said necked-in container from the dies.
9. The method of claim 8, comprising the further steps of effecting
successive necked-in end portions of said container by repeating
steps (a) through (c) of claim 1.
10. The method of claim 5, wherein the dimensional volume of said
reservoir is at least about equal or greater than the volume of the
metal container.
11. A method of necking an open end of a metal container,
comprising the steps of:
(a) positioning a reservoir of pressurized fluid into alignment
with the open end of the container, said reservoir having a
dimensional volume of pressurized fluid at least about equal tot he
volume of the container interior;
(b) flowing said pressurized fluid from the reservoir into the
interior; and
(c) contacting the open end with a necking die during step (b) to
thereby produce a necked-in open end, whereby rapid pressurization
of said container interior as a result of communicating the large
volume reservoir with the container interior during necking
stiffens the container to enable it to resist necking loading and
avoid being crushed.
12. The method of claim 11, comprising the further step of
continuously pressurizing the reservoir during step (b) from a
supply of pressurized fluid flowing thereto.
13. The method of claim 11, wherein said reservoir is located in a
pilot die, and comprising the further step of inserting the pilot
die into the container interior, opening a valve between the pilot
die and necking die to flow pressurized fluid into the
interior.
14. A method of necking a side wall forming an open end of a metal
can body with a necking apparatus having a die member and a pilot
coaxially located in the die member that engage the side wall to
form a neck in the can body, comprising the steps of:
(a) positioning the can body with its open end facing the necking
apparatus;
(b) driving the necking die member and the pilot longitudinally
forwardly along the axis of the can body so that the pilot enters
the open end of the can;
(c) stopping the movement of the pilot after it has entered the can
while continuing the movement of the die member to form a neck at
the open end of the can body between forward surfaces of the die
member and the pilot, wherein, during necking, pressurized fluid is
supplied into the can body interior through the pilot from a
reservoir of pressurized fluid within the pilot which is
continuously supplied with pressurized fluid from a supply of said
fluid flowing thereto during necking;
(d) beginning removal of the die member and of the pilot from the
can body by driving the die member rearwardly into contact with the
pilot with such contact preventing further admission of pressurized
fluid into the can body interior; and
(e) continuing the rearward movement of the die member and thereby
the pilot so that any pressurized fluid remaining within the can
body interior is released as the pilot disengages the necked-in can
body open end.
15. Apparatus for necking the side wall forming an open end of a
metal can body, comprising:
(a) a necking turret;
(b) a necking die mounted for longitudinal reciprocating movement
within said necking turret;
(c) a pilot assembly coaxially longitudinally reciprocatable within
said necking die and including a reservoir therewithin adapted to
supply fluid under pressure through the pilot assembly and into the
metal can body to pressurize the can and enable it to sustain
predetermined high necking loads without crushing, said reservoir
having a dimensional volume of pressurized fluid available for
immediate delivery to the can body interior at least about equal to
the volume of the can body to enable rapid pressurization to occur;
and
(d) means for driving the necking die and pilot assembly forwardly
toward the open end of the can body to contact the can side wall
and neck the can side wall at said open end thereof, and for
subsequently retracting the necking die and pilot assembly
rearwardly from the necked-in open end of the can body so that the
necked can be transferred to another work station.
16. Apparatus of claim 15, wherein said pilot assembly includes a
hollow pilot shaft containing the reservoir.
17. Apparatus of claim 16, wherein said reservoir extends
substantially the entire length of the pilot shaft.
18. Apparatus of claim 17, wherein the diameter of said reservoir
corresponds to the inner diameter of the pilot shaft.
19. Apparatus of claim 15, further comprising valve means, between
the pilot assembly and necking die, for controlling communication
between the reservoir and the can body to pressurize the can
interior.
20. Apparatus of claim 15, wherein the volume of the reservoir is
at least equal to the volume of a twelve ounce can body.
21. Apparatus of claim 15, further comprising means for rotating
the necking turret, said driving means including a cam rail
stationarily mounted adjacent the rotating turret, and cam follower
means engaging the cam rail to reciprocate the necking die and
pilot assembly.
22. Apparatus for necking the side wall forming an open end of a
metal can body, comprising:
(a) a necking turret;
(b) a necking die mounted for longitudinal reciprocating movement
within said necking turret;
(c) a pilot assembly coaxially longitudinally reciprocatable within
said necking die and including a reservoir therewithin adapted to
supply fluid under pressure through the pilot assembly and into the
metal can body to pressurize the can and enable it to sustain
predetermined high necking loads without crushing; and
(d) means for driving the necking die and pilot assembly forwardly
toward the open end of the can body to contact the can side wall
and neck the can side wall at said open end thereof, and for
subsequently retracting the necking die and pilot assembly
rearwardly from the necked-in open end of the can body so that the
necked can be transferred to another work station, further
comprising valve means, between the pilot assembly and necking die,
for controlling communication between the reservoir and the can
body to pressurize the can interior wherein said pilot assembly
includes a pilot shaft, and said valve means includes a valve
element mounted in a forward end of the pilot shaft and a plurality
of circumferentially spaced throughbores in the valve element for
high volume passage of pressurized fluid from the reservoir to the
can interior, said necking die including a valve disc contactable
with the valve element to selectively open and close the valve
means.
23. Apparatus of claim 22, wherein said driving means includes
means for initially driving the necking die and pilot shaft
forwardly together during forward travel toward the can body with
the valve disc in contact with the valve element to close the valve
means, and stop means for limiting forward travel of the pilot
shaft after the pilot assembly has entered the can interior through
the open end without effecting further forward travel of the
necking die into necking contact with the can side wall, whereby
said further forward travel moves the valve disc off the valve
element to open the valve means.
24. Apparatus of claim 23, wherein said valve means further
includes a forwardly extending portion on which rides the valve
disc, said forwardly extending portion including air passageway
means for communicating the throughbores with the can body interior
when the valve means is open.
25. Apparatus of claim 24, wherein said air passageway means
includes a plurality of radial passages formed adjacent the valve
element and a large diameter axial bore forwardly of the radial
passages for communicating same with said can interior.
26. Apparatus of claim 24, further comprising a guide block and
means for mounting said guide block to said forwardly extending
portion, said guide block including an outer cylindrical anvil
surface engaging the can side wall under the action of the necking
die to define the internal diameter of the necked-in portion of the
can body.
27. Apparatus of claim 26, wherein said necking die includes a
hollow spindle shaft in which said pilot shaft is coaxially
slidably mounted, a necking die mounting member mounted to the
forward end of the spindle shaft, and a necking die member mounted
to the mounting member in radially outwardly spaced relation to the
guide block.
28. Apparatus of claim 27, wherein said mounting member includes a
flange to which the valve disc is mounted in coaxial alignment with
the throughbores.
29. Apparatus of claim 28, further comprising a cam rail mounted
adjacent the necking turret and having a cam surface, wherein said
driving means includes a cam follower means, adapted to engage said
cam surface, for moving said necking spindle shaft in longitudinal
reciprocating strokes, said cam follower means including a cam
follower bracket to which a rear portion of the necking spindle
shaft is attached.
30. Apparatus of claim 29, wherein said cam follower bracket
includes a forwardly extending spring mounting member engaged with
the rear end of the pilot shaft mounted on the bracket, and spring
means connected to the spring mounting member for normally
forwardly biasing the pilot shaft so that the valve means is
closed.
31. Apparatus of claim 30, wherein the rear end of the pilot shaft
includes at least one radially extending projecting portion
extending through a corresponding longitudinal slot formed in the
rear end of the spindle shaft, wherein said necking spindle shaft
and pilot shaft are initially moved forward together by the cam
follower bracket until said radially outwardly projecting portion
engages said stop means, whereby said spindle shaft continues
forward travel under the action of the advancing cam follower
bracket as the now stationary projecting portion slides relatively
rearwardly through the slot as the valve means opens and the
necking die member advances into necking contact with the can
body.
32. Apparatus of claim 31, further comprising pressurized fluid
supply passageway means in said cam follower bracket for supplying
pressurized fluid to said reservoir.
33. Apparatus of claim 32, wherein the forwardly extending spring
mounting member defines the rearwardmost extent of the
reservoir.
34. Apparatus of claim 33, wherein said spring mounting member
terminates in a rear portion of the pilot shaft.
35. The apparatus of claim 22, wherein said reservoir has a
dimensional volume of pressurized fluid available for immediate
delivery to the can body interior at least about equal to the
volume of the can body to enable rapid pressurization to occur.
Description
TECHNICAL FIELD
The present invention relates generally to an improved method and
apparatus for the necking-in of side walls defining open ends of
metal can bodies in the manufacture of metal cans and, more
particularly, to an improved method and apparatus for static die
necking of metal can open ends in conjunction with introducing
compressed air into the can body interior to prevent crushing under
necking loads.
BACKGROUND ART
Static die necking is a process whereby the open ends of can bodies
are provided with a neck of reduced diameter utilizing a necking
tool having reciprocating concentric necking die and pilot
assemblies that are mounted within a rotating necking turret and
movable longitudinally under the action of a cam follower bracket
to which the necking die assembly is mounted. The cam follower
bracket thereby rotates with the turret while engaging a cam rail
mounted adjacent and longitudinally spaced from the rear face of
the necking turret. A can body is maintained in concentric
alignment with the open end thereof facing the necking tool of the
concentric die and pilot assemblies for rotation therewith. The
reciprocating pilot assembly is spring loaded forwardly from the
reciprocating die member. The forward portions of the die member
and pilot assembly are intended to enter the open end of the can
body to form the neck of the can.
More specifically, the die member is driven forwardly and, through
its spring loaded interconnection with the pilot assembly, drives
the pilot assembly forwardly toward the open end of the can. The
outer end of the pilot assembly enters the open end of the can in
advance of the die member to provide an anvil surface against which
the die can work. The forward advance of the pilot assembly is
stopped by the engagement of a homing surface on the necking turret
with an outwardly projecting rear portion of the pilot assembly,
slightly before the forward portion of the die member engages the
open end of the can. As the die member continues to be driven
forwardly by the cam, its die forming surface deforms the open end
of the can against the anvil surface of the pilot assembly to
provide a necked-in end to the can body.
A necking machine of the type discussed above is disclosed, for
example, in U.S. Pat. Nos. 4,457,158 and 4,693,108. In the latter
'108 patent, each necking station also has a container pressurizing
means in the form of an annular chamber formed in the pilot
assembly which acts as a holding chamber prior to transmitting the
pressurized fluid into the container from a central large reservoir
located in the necking turret. In the type of static die necking
discussed above to which the present invention pertains,
pressurized fluid internally of the container is critical to
strengthen the column load force of the side wall of the container
during the necking process. There are particular problems inherent
in introducing sufficient pressurized fluid into the container as
the speed of production is increased.
It is accordingly one object of the present invention to enable
rapid pressurization of the container body interior by air flowing
to it through the pilot assembly shaft.
Another object is to rapidly pressurize the can interior to sustain
high peak necking loading without crushing by placing a large
volume reservoir in the necking spindle assembly immediately
adjacent the can interior.
Still another object is to substantially instantaneously flow
pressurized air from the reservoir into the can interior through a
valve means having large diameter inlet ports communicating between
the reservoir and can interior.
DISCLOSURE OF THE INVENTION
Apparatus for necking the side wall forming an open end of a metal
can body, in accordance with the present invention, comprises a
necking turret and a necking die mounted for longitudinal
reciprocating movement within the turret. A pilot assembly is
coaxially longitudinally reciprocatable within the necking die. The
pilot assembly includes a reservoir adapted to supply fluid under
pressure through the pilot assembly and into the metal can body to
pressurize the can and enable it to sustain high necking loads
without crushing. The reservoir has a volume at least about equal
to the volume of the can body to enable rapid pressurization to
occur.
Means is provided for driving the necking die and pilot assembly
forwardly toward the open end of the can body to neck the can side
wall at the open end thereof, and for subsequently retracting the
necking die and pilot assembly rearwardly from the necked-in open
end of the can body so that the necked can may then be transferred
to another work station.
The pilot assembly preferably includes a hollow pilot shaft
containing the reservoir which may extend substantially the entire
length of the shaft. The diameter of the reservoir corresponds to
the inner diameter of the pilot shaft.
A pressurization valve is located between the pilot shaft and
necking die for controlling communication between the reservoir and
the can body to pressurize the interior. This control valve
preferably includes a valve element mounted in the forward end of
the pilot shaft and a plurality of circumferentially spaced
throughbores in the valve element for high volume passage of
pressurized fluid from the reservoir to the can interior. The
necking die includes a valve disc at its forward end which is
contactable with the valve element to selectively open and close
the valve means.
The driving means includes means for initially driving the necking
die and pilot shaft forwardly together toward the can body with the
valve disc in contact with the valve element to close the control
element. Stop means on the turret limits forward travel of the
pilot shaft after the pilot assembly has entered the can interior
through the open end. The necking die continues its forward travel
into necking contact with the can side wall. As this occurs, the
valve disc moves of the valve element to open the control
valve.
In a preferred embodiment, the control valve further includes a
forwardly extending portion on which rides the valve disc. The
forwardly extending portion contains air passageways for
communicating the throughbores with the can body interior when the
valve opens. The air passageways may be plural radial passages
formed adjacent the valve element and a large diameter axial bore
forwardly of the radial passages for communicating same with the
interior of the can.
The pilot assembly may further comprise a guide block and means for
mounting the guide block to the forwardly extending portion of the
valve means. The guide block includes an outer cylindrical anvil
surface engaging the can side wall under the action of the necking
die to define the internal diameter of the necked-in portion of the
can body by coacting with the die. The mounting member may include
a flange to which the valve disc is mounted in coaxial alignment
with the throughbores.
A method of necking an open end of a metal container, in accordance
with the present invention, comprising the steps of inserting a
pilot die into the container through the open end to be necked and
then contacting an exterior surface of the open end with a necking
die to thereby produce a necked-in portion. The interior of the
metal container is pressurized by admitting fluid into it at the
onset of necking. The fluid rapidly enters the interior in
sufficient quantity to withstand the necking loads from a reservoir
in the pilot, wherein the volume of the reservoir is at least about
equal to or greater than the volume of the metal container.
In accordance with a further feature of the invention, the
reservoir is preferably continuously pressurized during necking
from a supply of pressurized fluid flowing thereto.
In a preferred operating embodiment of the invention, the reservoir
is pressurized to about 60 psi which enables pressurization of the
container interior to about 20-25 psi within about 15
milliseconds.
Still other objects and advantages of the present invention will
become readily apparent to those skilled in this art from the
following detailed description, wherein only the preferred
embodiments of the invention are shown and described, simply by way
of illustration of the best mode contemplated of carrying out the
invention. As will be realized, the invention is capable of other
and different embodiments, and its several details are capable of
modifications in various obvious respects, all without departing
from the invention. Accordingly, the drawing and description are to
be regarded as illustrative in nature, and not as restrictive.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a cross-sectional view through a necking station of a
necking die constructed in accordance with the principles of the
present invention;
FIG. 2 is a sectional view similar to FIG. 1 but on an enlarged
scale to depict further specifics of the cam drive and follower
assembly at each necking station;
FIG. 3 is an enlarged sectional view depicting the pilot and
necking guide assemblies at their end of stroke necking
positions;
FIG. 3A is a sectional view taken along the line 3A--3A of FIG.
3;
FIG. 4 is a sectional view depicting the pilot and necking die
assemblies in their relative locations at the commencement of the
forward necking stroke;
FIG. 5A is a sectional, sequential view depicting the pilot
assembly as it just travels into its forwardmost position within
the can open end and the necking die prior to engaging the can side
wall;
FIG. 5B is a sequential view similar to FIG. 5A as the necking die
travels into initial necking contact with the can side wall with
the pressurized air valve beginning to open;
FIG. 5C is a sequential view similar to FIG. 5B depicting the
necking die in its forwardmost travel position whereupon the side
wall is necked-in; and
FIG. 5D is a sequential view similar to FIGS. 5A--5C immediately
after retraction of the pilot and necking die assemblies.
BEST MODE FOR CARRYING OUT THE INVENTION
Die necking apparatus, generally indicated by reference numeral 10,
will, in the position depicted in FIG. 1, neck in and reduce the
diameter of a can body 12 by axially advancing into contact with
the open end 14 thereof under the action of a cam 16. Die necker 10
includes a necking spindle assembly 18 slidably mounted for
reciprocating longitudinal movement in an axial throughbore 20 of a
rotating necking turret 22. A pilot assembly 24, coaxially carried
within the necking spindle assembly 18, is initially longitudinally
advanced (FIG. 5A) into the can open end 14 under the action of a
cam follower bracket 26 engaging cam 16. Cam follower bracket 26 is
connected to the rear end 28 of spindle assembly 18 to then
longitudinally advance a necking die 30, mounted to the front end
32 of the spindle assembly, into contact with the marginal edge of
the open can end 14. As will be seen more fully below, the pilot
assembly 24 features a unique air pressure reservoir 34 and disc
valving arrangement 36 which rapidly transmits pressurized air into
the can body interior 38 through the open end 14 being necked to
ensure that the can 12 has sufficient rigidity when contacted by
the necking die 30.
The rotating necking turret 22 is of cylindrical cast construction
adapted to be mounted via flange or pilot diameter 40 (FIG. 1) for
rotation about a central horizontal axis of rotation L. The
plurality of axial throughbores 20, each housing a necking spindle
assembly 18, are circumferentially spaced from each other within
the periphery of the turret 22 in parallel equispaced relationship
to the axis of rotation L. The cam 16 is in the form of a
stationary cam rail mounted to a bracket F which is mounted to a
side frame of the machine as schematically depicted in FIG. 2 and
as is well known. Reciprocating movement is imparted to each
necking spindle assembly 18 through a driving arrangement connected
to the cam follower bracket 26 and having a pair of rollers 44 and
46 which are driven from the cam rail 16 passing between them. It
will be understood that the relative axial spacing of the cam rail
16 from rear face 22a of the necking turret 22 varies as a function
of the angular position of the necking spindle assembly 18 during
its rotation about turret axis L to thereby control the degree of
longitudinal reciprocating movement of the necking die 30 and pilot
assembly 24 in the manner set forth more fully below.
Although not shown in detail, the unnecked can bodies 12 are fed in
a known manner onto a star transfer wheel 50 where the cans are
individually held by vacuum in pockets 52 circumferentially spaced
along the periphery of the wheel in respective coaxial alignment
with each necking spindle assembly 18. Each can body 12 has a
profiled bottom of known cross-section adapted to be engaged and
held in an axially stationary position by means of a retractable
bottom support assembly 54 which may be of known construction.
During the necking operation, star wheel 50 and bottom support
assembly 54 co-rotate with necking turret 22 to maintain coaxial
alignment between the necking spindle assembly 18 and the ca
longitudinal axis L1.
Referring to FIGS. 1 and 2, each necking spindle assembly 18
comprises a spindle housing in the form of a hollow shaft 56
disposed in the axial throughbore 20 of the turret in sliding
contact with spindle housing bushings 58 mounted at opposite ends
of each throughbore. The front end 32 of the spindle housing 18
projects forwardly from the axial throughbore 20 and carries a
necking die holder 60 having a cylindrical forwardly extending die
mounting portion 62 and a rear radially inward extending mounting
flange portion 64 bolted to the front end 32 of the hollow shaft 56
with a plurality of mounting bolts 66. As best depicted in FIG. 3,
the die mounting portion 62 supports the cylindrical necking die
element 30 having a rearwardly projecting portion interfitting with
the die mounting portion in press fitting engagement. The
forwardmost annular portion of the necking die element 60 has a die
forming surface 70 of known configuration for contacting the
marginal edge 14 of the open end of the can to neck the same during
forward movement of the necking spindle shaft 56 under the action
of cam 16.
The mounting flange 64 of the die holder 60 further includes a
radially inwardly extending valve disc holder 72 defining an
annular rearward facing ledge 72a adapted to receive an annular
valve disc 74 fitted therein for purposes described
hereinafter.
The rear end 28 of the spindle housing shaft 56 is formed with a
radially outward mounting flange 80 (FIG. 2) adapted to be bolted
to the cam follower bracket 26 as at 82. The die forming surface 70
and the valve disc 74 thereby reciprocate longitudinally through
motion imparted to the spindle housing shaft 56 by the cam follower
bracket 26 and rollers 44,46 from the cam 16 during rotation of the
necking turret 22 about its horizontal rotational axis L. The
spindle housing shaft 56 is prevented from rotating about its axis
L1 through a key 83 bolted to turret 22 and received in a slotted
side wall 82a of the spindle shaft.
The pilot assembly 24 is a hollow shaft 85 coaxially mounted within
the spindle housing shaft 56 and supported for relative sliding
movement through a pair of bushings 86 disposed at opposite ends of
the spindle housing shaft. The pilot shaft 85 has at its rear end a
co-acting means in the form of a pair of radially outwardly
projecting portions 88 extending through a corresponding pair of
slots 90 formed in the rear end 28 of the spindle housing shaft 56
just forwardly of the mounting flange 80. As shown in FIG. 1, the
outwardly projecting co-acting portions 88 will engage, at their
front radial faces 88a, a stationary bumper ring 92 mounted to the
rear face 22a of the necking turret 22 as the pilot assembly 24 is
moved forwardly by the cam follower bracket 26 into its forwardmost
position limited by the bumper ring 92.
As the die member 30 is still moved forwardly by the cam follower
bracket 26, the arrested motion of the pilot shaft 85 compresses a
spring 94 extending between a spring guide 96, mounted within the
hollow pilot shaft 85, and forwardly axially extending portion
(spring mounting member) 98 of the cam follower bracket 26 received
within the rear end 100 of the pilot shaft 85. The rear end 100 of
the pilot shaft 85 is slidable with respect to the forward portion
98 of the cam follower bracket 26 extending coaxially therewithin.
The forwardmost portion 102 of the spring mounting member 98 is of
reduced diameter for insertion in the rear end of the spring 94 and
also defines a forward-facing annular spring engaging surface 104
against which the rearwardmost end of the spring 94 rests. This
spring engaging surface 104 is actually defined by a pair of thrust
washers 106. A bushing 108 is disposed between the spring mounting
portion 98 of the cam follower bracket 26 and the inner surface of
the rear end 100 of the pilot shaft 85, forwardly of the outwardly
projecting portions 88.
The spring guide 96 is maintained in an axially stationary position
within the pilot shaft 85 by means of a rear facing annular ledge
110 engaging the forwardmost peripheral edge 112 of the spring
guide. The rearwardmost portion 114 of the spring guide 96 is of
reduced diameter (corresponding to the reduced diameter of the
forwardmost portion 102 of the spring holder 98) to define a
rearward facing annular surface 116 receiving the front end 118 of
the spring 94. This rearward surface 116 defines a spring driven
surface which, during initial forward movement of the cam follower
bracket 26, acts to drive the pilot shaft 85 forwardly through the
compressive force of the spring 94 transmitted to the spring guide
96 through the forwardly moving spring holder 98 of the cam
follower bracket until the outwardly projecting portions 88 of the
pilot shaft 85 engage the rearward facing stop surfaces 92a of the
stationary bumper ring 92. At that time, the die member 30 is still
moved forwardly by the cam follower bracket 26 and this motion
compresses the spring 94 between the spring engaging surface 104 of
the spring holder 98 and the spring driven surface 116 of the
spring guide 96.
In accordance with a unique feature of this invention, the interior
hollow region of the pilot shaft 85 functions as a pressurized air
reservoir 34 which is continuously supplied with pressurized air
during the necking process through a longitudinally extending
passageway 120 formed in the spring holder 98 of the cam follower
bracket 26 which intersects a radially extending passageway 122
formed in a radially extending portion 124 of the cam follower
bracket to which portion the rear mounting flange 80 of the spindle
housing shaft 56 is bolted. A radially outermost end of the radial
supply passage 122 has an inlet port 126 adapted to constantly
communicate during necking with a source of pressurized air
supplied to it through a fitting (not shown). The forwardmost end
120a of the longitudinally extending passage 120 communicates with
the hollow interior region 34 of the pilot shaft 85 to constantly
supply the pressurized air into the reservoir. By making the spring
guide 96 hollow, virtually the entire length (i.e., from spring
holder 98 to front end 85a) of the interior hollow region of the
pilot shaft 85 may be utilized as a pressurized air reservoir
34.
The front end 85a of the pilot shaft 85 receives a unique valving
element 130 formed with a plurality of axial throughbores 132
circumferentially spaced from each other along the periphery of the
cylindrical valving element (FIG. 3A). In the unique manner
described more fully below, the pressurized air within the
reservoir 34 formed exclusively within the hollow interior region
of the pilot shaft 85 is adapted to flow through these supply
throughbores 132 into radially extending cross drilled passageways
134 formed in an axially forwardly extending portion 136 of the
valving element 130. These axial supply throughbores 132 are
selectively closed by the valve disc 74 prior to die necking as
described infra.
A cylindrical guide block holder 140 has a rearwardly extending
portion 142 encircling, and supported by, the forwardmost portion
136 of the valving element 130. As best depicted in FIG. 3, a
leading portion 144 of the holder 140 projects forwardly from the
front end of the valving element 136. A stationary cylindrical
guide block 148 defining the forwardmost end of the pilot assembly
24 is mounted to a forwardly extending reduced diameter hub portion
150 of the guide block holder 140 with a bolt as at 152. A pair of
seals 154 are disposed between the guide block holder 140 and the
inner mounting surface 148a of the guide block 148 to prevent
leakage of pressurized air from the can interior from between these
surfaces during necking. The axially extending cylindrical outer
surface 160 of the guide block 148 functions as an anvil during the
necking process and defines the necked-in diameter of the can open
end 14.
In operation, prior to necking (FIG. 4), the can body 12 is
positioned by the star wheel 50 and the can bottom support 54
opposite the spindle assembly 18. With the can 12 in position, the
spindle shaft 56 and the pilot shaft 85 are initially located
relative to each other so that the valve disc 74 abuts against the
air supply holes 132 of the valving element 130 to shut off the
pressurized air supply to the can interior 38. The forward facing
surfaces 88a of the rear outwardly projecting portions 88 of the
pilot shaft 85 are spaced from the rear stop surfaces 92a of the
bumper ring 92 under the action of the valve disc 74 which is
stationary in the forward end of the spindle shaft 56. Residual
compression in the compression spring 94 acts through the spring
guide 96 to maintain the forward end 85a of the pilot shaft 85 and
the supply holes 132 in tight sealing abutment with the valve disc
74.
As the necking turret 22 and thereby the spindle housing 18 and the
can 12 co-rotate about axis L relative to the stationary cam 16,
the die member 30 and the guide block 148 begin to advance axially
forward together through forward movement transmitted to the
spindle housing shaft 56 through the cam follower rolls 44,46 and
cam follower bracket 26 and to the pilot shaft 85 through the
compression spring 94 acted upon by the spring holder portion 98 of
the cam follower bracket. The compression spring 94 is of
sufficient stiffness to transmit such forward motion of the spring
holder 98 to the pilot shaft 85. The forward movement of the die
member 30 and its spring engaging surface 104 moves the pilot
assembly 24 forwardly so that the guide block 148 enters the open
end 14 of the can 12 as best depicted in FIG. 5A. After the pilot
assembly 24 has travelled into the open end 14 of the can 12 for a
predetermined distance, the forward faces 88a of the outwardly
projecting coacting means 88 at the rear of the pilot shaft 85
contact the rearward stop surfaces 92a of the bumper ring 92 (FIG.
2) stationarily mounted to the rotating necking turret 22, thereby
stopping the forward travel of the pilot assembly and positioning
the outer cylindrical anvil surface 160 of the guide block 148
within the open end of the can body. At this point in its forward
travel, the die forming surfaces 70 at the forward end of the die
member 30 have not yet begun its deformation of the can body open
end 14. However, it is to be understood that the valve disc 74
starts to open as soon as 88 hits 92 and before open end 14 hits
anvil 160. Since the can edge 14 is inside the die 30 in sealed or
air tight contact therewith at this point, air pressure in the can
body begins to build.
As the necking turret 22 rotates further, the die forming surfaces
70 continue to axially advance into initial deforming contact (FIG.
5B) with the side wall defining open end 14 of the can body 12.
This occurs under the action of further advancing movement of the
spindle housing shaft 56 through the advancing cam follower bracket
26 and cam follower rollers 44,46 engaging the cam rail 16.
At this point, the die forming surfaces 70 begin to deform the open
end 14 of the can body 12 against the coaxial anvil surfaces 160 of
the now stationary guide block 148 to provide a necked-in portion
of the can body.
Rapid pressurization of the can interior, prior to necking,
advantageously occurs both by unique placement of the large volume
reservoir 34 in the necking die and by high speed flow of air
through the valve. The feature of plural air supply throughbores
132 in the now stationary valving element 130 enables pressurized
air to be rapidly released into the can interior 38 from the air
reservoir 34 through these air supply holes (i.e., which are open
once coacting means 88 contacts bumper ring 92) and into the cross
drilled transverse passageways 134 and thence through the large
diameter longitudinal air passageway 200 of the valving element 136
communicating at its rear end with the cross drilled passageways
134. This longitudinal air passageway 200 communicates with a like
diameter longitudinal passageway 202 formed in the guide block
holder 140 which enables the air to enter the can interior 38.
The compressed air entering the can body 12 in the aforesaid manner
will pressurize the can body and tends, through the pressure and
force acting on the base of the can, to force the can away from the
necking apparatus 10. However, since the can 12 is held stationary
with respect to the apparatus 10 by the bottom support assembly 54,
the pressurized air in the container acts to ensure that the
container has sufficient rigidity when contacted by the necking die
30 to avoid buckling. The can 12 is therefore rapidly pressurized
to a pressure which is based upon the pressure within the air
reservoir 34 (e.g., 60 psi). As the die forming surface 70
continues to advance (FIG. 5C) through the action of the cam 16 and
cam follower bracket 26, the guide block 148 through the pilot
shaft 85 continues to be stationary because the outwardly
projecting portions 88 of the pilot shaft are captured against
bumper ring 92 with the motion of the spring holder 98 of the cam
follower bracket being taken up by the compressing spring 94. The
pressure within the can interior is maintained at the same level as
the air pressure within the reservoir 34 until after the die
forming surfaces 70 advance to the end of stroke position depicted
in FIGS. 1, 3 and 5C. At this point, the die forming surfaces 70
begin to retract (FIG. 5D) through the rearward motion now imparted
to the spindle housing shaft 56 through the cam follower bracket 26
acted upon by the cam follower rolls 44,46 through the cam 16. As
the valve disc 74 retreats into abutting contact with the front end
of the pilot shaft 85, the air supply holes 132 are sealed.
Continued retreating movement of the spindle housing 56 now causes,
through the valve disc 74 pressing against the front end 85a of the
pilot shaft, corresponding retreating movement of the pilot shaft
85 and thereby the guide block 148 from the necked-in open end 14.
The compressed air is released from the can interior 38 through the
open end 14 around the retreating guide block 148. When the can 12
is free of the necking apparatus 10, it may be moved using known
means to the next station (e.g., flanging).
As mentioned above, it is one important feature of the present
invention to provide the pressurized air reservoir 34 within the
necking spindle assembly 18, and particularly within the pilot
shaft hollow region, to enable rapid pressurization of the can
interior 38. Such rapid pressurization is necessary to avoid can
buckling during the die necking process. As a result of extensive
experimentation, it has been discovered that high peak axial
loading of the can body 12 occurs as the open end 14 of the can
curves around the radially inwardly tapered area of the die forming
surfaces 70 as at 210 in FIG. 5B and strikes the anvil surfaces 160
of the guide block 148. At a nominal can forming speed of 2,000
cans per minute (CPM), it takes approximately only 15 milliseconds
from the time the die forming surfaces 70 seals the can until the
edge of the can contacts the guide block anvil surfaces 160 to seal
the can interior 38. At the end of this elapsed predetermined time
interval, it is necessary for the can interior 38 to be pressurized
to a predetermined pressure (e.g., 20-25 psi) so as to adequately
stiffen the can and better enable it to resist necking loading and
avoid being crushed during the necking process.
Therefore, by locating the pressurized air reservoir 34 within the
necking spindle assembly 18, i.e., in close proximity to the can
body interior 38, a large volume of pressurized air is
substantially instantaneously available to be supplied into the can
body interior through the disc controlled valve 130 of the present
invention. The dimensional or physical volume of the reservoir 34
is preferably at least equal to the interior volume 38 of the can
body (e.g., typically twelve ounces for a standard size beverage
can) and is preferably 100 percent of a volume of a standard size
beverage container to ensure rapid can pressurization.
From a review of this disclosure, it will now be appreciated that
the air pressure within the reservoir 34 is continuously maintained
at a predetermined level (e.g., 60 psi) throughout necking so as to
enable rapid pressurization of the can 12 during the aforementioned
critical period when the can must be quickly pressurized to a
predetermined level to enable the can to sustain high peak loading
without crushing.
Another important and preferred feature of this invention is the
unique disc controlled valve 130 which must enable rapid
pressurization of the can body interior 38 by air flowing through
it from the reservoir 34. The feature of providing a plurality of
circumferentially spaced air supply through-holes 132
advantageously enables a large volume of air to flow from the
reservoir 34 through the holes towards the can interior 38. The
cross drilled passageways 134 (e.g., four circumferentially spaced
passageways) which may be of larger diameter than the air supply
holes 132, provide an effective means for enabling air supply from
the throughbores to continue its high volume passage into the can
interior 38. This passage is completed by the large diameter axial
throughbore 200 extending through the remainder of the valving
element 136 from a large diameter point of intersection with the
cross drilled transverse passageways 134.
It will now occur to one of ordinary skill in the art that the
large cross sectional area of the central throughbore 200 may be
machined to correspond to the total cross sectional area of the
cross drilled passageways 134 and that these passageways in turn
may be machined so that their total cross sectional area
corresponds to that of the total cross sectional area of the air
supply throughbores 132. In this manner, high volume flow rates of
pressurized air may be reliably maintained through the unique valve
of this invention from the reservoir 34 to the can body interior
38.
The feature of continuously supplying pressurized air into the
reservoir 34 through the cam follower bracket 26 assists in rapid
pressurization of the can body interior 38 by minimizing or
preventing pressure drop within the air reservoir to enable high
speed necking to occur.
Another unique feature of this invention is the provision of air
vacuum passageways, schematically depicted at 250 in FIG. 1, within
the star wheel 50 which communicate with the pockets 52 to retain
the can bodies on the star wheel with vacuum. Based upon a review
of the instant specification, the manner in which the vacuum is
supplied to each pocket 52 through vacuum passageways 250 from a
vacuum source 252 will readily occur to one of ordinary skill in
the art. The feature of holding the cans 12 in the pockets 52 with
vacuum allows for the elimination of guide rails (not shown) which
in turn eliminates the likelihood of jams from occurring between
the guide rails and the cans as in the prior art.
In accordance with another feature of the instant invention, the
spindle throughbores 20 formed in the necking turret 22 are
preferably commonly bored with the pockets 52 to ensure perfect
alignment between the die forming surfaces 70 and the central
longitudinal axis L1 of the can body 12. Since the can bodies 12 do
not rotate during the die necking process in this invention, it
will be appreciated that the can body is centered relative to the
spindle housing 18 through contact between the machined surface of
the pocket with the outer surface of the can body.
It will be readily seen of one of ordinary skill in the art that
the present invention fulfills all of the objects set forth above.
After reading the foregoing specification, one of ordinary skill
will be able to effect various changes, substitutions of
equivalents and various other aspects of the inventions as broadly
disclosed herein. It is therefore intended that the protection
granted hereon be limited only by the definition contained in the
appended claims and equivalents thereof.
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